Medical implants are frequently coated with metals, polymers or other materials. Over time, some of these materials may shed small particles that could cause embolic episodes in the cardiovascular system or osteonecrosis in orthopedic applications. Manufacturers of medical implants are required to test the long term durability of their products, for example, to assess structural fatigue. However, current testing requirements do not call for reporting of particle shed rates.
Current technology for determining particle shed rates of implantable medical devices includes running a standard durability test, which for heart-related devices may replicate approximately 400 million heartbeats. The fluid from the test is collected and then filtered with any particles in the fluid being counted. This method suffers from several drawbacks. For example, in tests involving multiple devices, it is impossible to determine which device is shedding. Further, overall particle shed rates may be inaccurate because some medical product coatings are biodegradable and may not survive the testing, which can last several months. Also, these methods do not teach when shedding occurs and may not be precise with regard to shed particle size devolvement, for example, where large particles may become dislodged and then break apart.